Someone is killing members of the royal family of a small European principality who's lives are insured by Lime Steet. In order to protect the sole remaining heir, Christina, Grey agrees to take her back to the United States to his farm. But the assassin follows them across the Atlantic.

The cockpit crew of a 747 stage a hijacking in order to extort four million dollars from their airline, then plant evidence that points to D.B. Cooper. Grey and Eddie see through their plot, but to prove their case they must first figure out how the crew got the ransom off the airplane after it landed and was beseiged by FBI agents.

Grey is in England with his daughters on vacation when a train disappears on it's last run before being placed into a museum. He and Eddie are assigned the case and soon turn up evidence that leads all the way back to a military payroll robbery that occured decades earlier aboard the same train.

In Amsterdam, a fortune in jewels are stolen from the high-tech safe of a broker. Grey and Eddie fly in to track down the culprit and end up suspecting two hick sisters from Arkansas who claim to be on vacation.

Grey and Eddie are dispatched to Switzerland where an extortionist is threatenig a prestigious hotel chain. He is demanding millions of dollars or he'll set off a bomb, leaving the Lime Street investigators racing against the clock to track him down.

As a publicity stunt, a novelist writes a book containing clues that can lead readers to a real life treasure. Eventually, a reader discovers the location of the buried loot, but when the treasure chest is opened amidst a flurry of reporters and news crews, the only thing inside is the body of the writer. Grey and Eddie must hunt down the killer and retrieve the treasure or Lime Street will have to pay off the contest winner.

Grey and Eddie's latest case involves a man named James Edwards, who claims he can communicate with the dead. Things turn grave when the expert they hire to disprove the psychic's ability turns up dead. The investigators must prove that Edwards murdered him to keep from being discredited, or Lime Street will have to pay him $3 million.